1. Field of the Invention
The present invention relates to a door assembly which opens and closes a heating chamber of home appliance, to an electric oven employing the door assembly, and to method for operating the electric oven.
2. Discussion of the Related Art
Electric oven is an apparatus which heats food deposited in a heating chamber thereof using heaters operable by electricity, such as, a ceramic heater, a sheath grill heater, and/or a halogen heater.
Electric oven can cook food quickly and has a high thermal efficiency. In addition, electric oven is relatively safe from a fire started by a flame compared to gas oven. Therefore, electric oven gets more popular nowadays.
Meanwhile, dirt including ingredient of food and oil sticks to inner walls of the heating chamber of the electric oven while cooking. It is hard for the user to clean the dirt stuck to the inner walls of the heating chamber. Therefore, some electric ovens provide a special function which automatically cleans the inner walls of the heating chamber.
During the operation of the electric oven in an automatic cleaning mode, heaters of the electric oven heats up the heating chamber to a very high temperature, for example, over 450 degree Celsius higher than a temperature from 100 to 300 degree Celsius at which food is cooked. Therefore, the dirt stuck to the inner walls of the heating chamber is pyrolyzed and carbonized during the automatic cleaning mode. After the electric oven finishes the automatic cleaning mode, the user can easily remove carbonized dirt from the inner walls of the heating chamber by sweeping it with a brush.
Heat in the heating chamber is transferred to a door which opens and closes the heating chamber when the heaters heat up the heating chamber to cook food or to clean the inner walls of the heating chamber. Because the door is also heated by the heaters during the operation of the electric oven, the user may get a burn in case he/she accidentally touches the door during the operation of the electric oven, especially in the automatic cleaning mode.
In order to solve this problem, some electric ovens automatically cool down the door during the operation of the electric oven. These electric ovens include a fan that forms air flows running through an inner space of the door during the operation of the electric oven. The air flow generated by the fan usually cools down an inner surface of the door as well as an outer surface of the door while running through the inner space of the door. Therefore, the heating chamber as well as the door is cooled down by the air flow running through the door.
Accordingly, thermal efficiency of electric oven decreases when the fan cools the door during the operation of the electric oven. In addition, food deposited in the heating chamber is not evenly cooked because an area in the heating chamber adjacent to the door is so cooled compared to another area in the heating chamber opposite to the side adjacent to the door. Further, cooking time of electric oven increases.